Our recent work has shown that lysolecithin extraction of submitochondrial particles followed by differential centrifugation yields an ATPase complex (FO-F1) preparation with a reasonable degree of purity and high Pi-ATP exchange activity. This project is designed to further purify this FO-F1 preparation to study the subunit arrangement and spatial relationships of the various subunits of the membrane sector proteins. It is hoped that the data would provide clues to the elucidation of mechanism of energy coupling process that require intimate association of F1 and membrane components. The topology of Fo-proteins will be studied utilizing bifunction cross-linking as well as photoaffinity reagents and the adducts will be identified with the help of site specific labels. Sub-unit specific antibodies and gel electrophoresis.